1、Designation: C31/C31M 15a1Standard Practice forMaking and Curing Concrete Test Specimens in the Field1This standard is issued under the fixed designation C31/C31M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1NOTEEditorial corrections were made in February 20
3、16.1. Scope*1.1 This practice covers procedures for making and curingcylinder and beam specimens from representative samples offresh concrete for a construction project.1.2 The concrete used to make the molded specimens shallbe sampled after all on-site adjustments have been made to themixture propo
4、rtions, including the addition of mix water andadmixtures. This practice is not satisfactory for making speci-mens from concrete not having measurable slump or requiringother sizes or shapes of specimens.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as sta
5、ndard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, as
6、sociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to exposed s
7、kin and tissue upon prolongedexposure.2)1.5 The text of this standard references notes which provideexplanatory material. These notes shall not be considered asrequirements of the standard.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete Ag-gregatesC138/C
8、138M Test Method for Density (Unit Weight), Yield,and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-CementConcreteC172/C172M Practice for Sampling Freshly Mixed Con-creteC173/C173M Test Method forAir Content of Freshly MixedConcrete by the Volumetric MethodC231/C
9、231M Test Method forAir Content of Freshly MixedConcrete by the Pressure MethodC330/C330M Specification for Lightweight Aggregates forStructural ConcreteC403/C403M Test Method for Time of Setting of ConcreteMixtures by Penetration ResistanceC470/C470M Specification for Molds for Forming ConcreteTest
10、 Cylinders VerticallyC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC617/C617M Practice for Capping Cylindrical ConcreteSpecimensC1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement Co
11、ncreteC1077 Practice for Agencies Testing Concrete and ConcreteAggregates for Use in Construction and Criteria forTesting Agency Evaluation1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.61on Testi
12、ng for Strength.Current edition approved Nov. 15, 2015. Published January 2016. Originallyapproved in 1920. Last previous edition approved in 2015 as C31/C31M15. DOI:10.1520/C0031_C0031M-15A.2See Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, V
13、ol. 04.02.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of
14、 this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 American Concrete Institute Publication:4309R Guide for Consolidation of Concrete3. Terminology3.1 For definitions of terms used in this practice, refer toTerminology C
15、125.4. Significance and Use4.1 This practice provides standardized requirements formaking, curing, protecting, and transporting concrete testspecimens under field conditions.4.2 If the specimens are made and standard cured, asstipulated herein, the resulting strength test data when thespecimens are
16、tested are able to be used for the followingpurposes:4.2.1 Acceptance testing for specified strength,4.2.2 Checking adequacy of mixture proportions forstrength, and4.2.3 Quality control.4.3 If the specimens are made and field cured, as stipulatedherein, the resulting strength test data when the spec
17、imens aretested are able to be used for the following purposes:4.3.1 Determination of whether a structure is capable ofbeing put in service,4.3.2 Comparison with test results of standard cured speci-mens or with test results from various in-place test methods,4.3.3 Adequacy of curing and protection
18、of concrete in thestructure, or4.3.4 Form or shoring removal time requirements.5. Apparatus5.1 Molds, GeneralMolds for specimens or fasteningsthereto in contact with the concrete shall be made of steel, castiron, or other nonabsorbent material, nonreactive with concretecontaining portland or other h
19、ydraulic cements. Molds shallhold their dimensions and shape under all conditions of use.Molds shall be watertight during use as judged by their abilityto hold water poured into them. Provisions for tests of waterleakage are given in the Test Methods for Elongation,Absorption, and Water Leakage sect
20、ion of Specification C470/C470M. A suitable sealant, such as heavy grease, modelingclay, or microcrystalline wax shall be used where necessary toprevent leakage through the joints. Positive means shall beprovided to hold base plates firmly to the molds. Reusablemolds shall be lightly coated with min
21、eral oil or a suitablenonreactive form release material before use.5.2 Cylinder MoldsMolds for casting concrete test speci-mens shall conform to the requirements of SpecificationC470/C470M.5.3 Beam MoldsBeam molds shall be of the shape anddimensions required to produce the specimens stipulated in 6.
22、2.The inside surfaces of the molds shall be smooth. The sides,bottom, and ends shall be at right angles to each other and shallbe straight and true and free of warpage. Maximum variationfrom the nominal cross section shall not exceed 3 mm 18 in.for molds with depth or breadth of 150 mm 6 in. or more
23、.Molds shall produce specimens at least as long but not morethan 2 mm 116 in. shorter than the required length in 6.2.5.4 Tamping RodA round, smooth, straight, steel rod witha diameter conforming to the requirements in Table 1. Thelength of the tamping rod shall be at least 100 mm 4 in.greater than
24、the depth of the mold in which rodding is beingperformed, but not greater than 600 mm 24 in. in overalllength (see Note 1). The rod shall have the tamping end or bothends rounded to a hemispherical tip of the same diameter as therod.NOTE 1A rod length of 400 mm 16 in. to 600 mm 24 in. meets therequi
25、rements of the following: Practice C31/C31M, Test Method C138/C138M, Test Method C143/C143M, Test Method C173/C173M, and TestMethod C231/C231M.5.5 VibratorsInternal vibrators shall be used. The vibratorfrequency shall be at least 150 Hz 9000 vibrations per minutewhile the vibrator is operating in th
26、e concrete. The diameter ofa round vibrator shall be no more than one-fourth the diameterof the cylinder mold or one-fourth the width of the beam mold.Other shaped vibrators shall have a perimeter equivalent to thecircumference of an appropriate round vibrator. The combinedlength of the vibrator sha
27、ft and vibrating element shall exceedthe depth of the section being vibrated by at least 75 mm 3in. The vibrator frequency shall be checked periodically witha vibrating-reed tachometer or other suitable device.NOTE 2For information on size and frequency of various vibratorsand a method to periodical
28、ly check vibrator frequency see ACI 309R.5.6 MalletA mallet with a rubber or rawhide head weigh-ing 0.6 6 0.2 kg 1.25 6 0.50 lb shall be used.5.7 Placement Toolsof a size large enough so each amountof concrete obtained from the sampling receptacle is represen-tative and small enough so concrete is n
29、ot spilled duringplacement in the mold. For placing concrete in a cylinder mold,the acceptable tool is a scoop. For placing concrete in a beammold, either a shovel or scoop is permitted.5.8 Finishing Toolsa handheld float or a trowel.5.9 Slump ApparatusThe apparatus for measurement ofslump shall con
30、form to the requirements of Test MethodC143/C143M.5.10 Sampling ReceptacleThe receptacle shall be a suit-able heavy gauge metal pan, wheelbarrow, or flat, cleannonabsorbent board of sufficient capacity to allow easy remix-ing of the entire sample with a shovel or trowel.5.11 Air Content ApparatusThe
31、 apparatus for measuringair content shall conform to the requirements of Test MethodsC173/C173M or C231/C231M.4Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.aci-int.org.TABLE 1 Tamping Rod Diameter RequirementsDiameter of Cylinderor Width
32、of Beammm in.Diameter or Rodmm in.200 8 3 or more equal depths,each not to exceed150 mm 6 in.see 9.3TABLE 5 Molding Requirements by VibrationSpecimen Typeand SizeNumber ofLayersNumber ofVibratorInsertionsper LayerApproximate Depth ofLayer, mm in.Cylinders:Diameter, mm in.100 4 2 1 one-half depth of
33、specimen150 6 2 2 one-half depth of specimen2256 9 2 4 one-half depth of specimenBeams:Width, mm in.100 4 to200 81 see 9.4.2 depth of specimenover 200 8 2 or more see 9.4.2 200 8 as near aspracticableC31/C31M 15a14level with the rim or edge of the mold and that has nodepressions or projections large
34、r than 3.3 mm 18 in.9.5.1 CylindersAfter consolidation, finish the top surfacesby striking them off with the tamping rod where the consis-tency of the concrete permits or with a handheld float or trowel.If desired, cap the top surface of freshly made cylinders with athin layer of stiff portland ceme
35、nt paste which is permitted toharden and cure with the specimen. See section on CappingMaterials of Practice C617/C617M.9.5.2 BeamsAfter consolidation of the concrete, use ahandheld float or trowel to strike off the top surface to therequired tolerance to produce a flat, even surface.9.6 Identificat
36、ionMark the specimens to positively iden-tify them and the concrete they represent. Use a method thatwill not alter the top surface of the concrete. Do not mark theremovable caps. Upon removal of the molds, mark the testspecimens to retain their identities.10. Curing10.1 Standard CuringStandard curi
37、ng is the curingmethod used when the specimens are made and cured for thepurposes stated in 4.2.10.1.1 StorageIf specimens cannot be molded at the placewhere they will receive initial curing, immediately afterfinishing move the specimens to an initial curing place forstorage. The supporting surface
38、on which specimens are storedshall be level to within 20 mm/m 14 in. ft. If cylinders in thesingle use molds are moved, lift and support the cylinders fromthe bottom of the molds with a large trowel or similar device.If the top surface is marred during movement to place of initialstorage, immediatel
39、y refinish.10.1.2 Initial CuringImmediately after molding andfinishing, the specimens shall be stored for a period up to 48 hin a temperature range from 16 to 27C 60 to 80F and in anenvironment preventing moisture loss from the specimens. Forconcrete mixtures with a specified strength of 40 MPa 6000
40、psi or greater, the initial curing temperature shall be between20 and 26C 68 and 78F. Various procedures are capable ofbeing used during the initial curing period to maintain thespecified moisture and temperature conditions. An appropriateprocedure or combination of procedures shall be used (Note 8)
41、.Shield all specimens from the direct sunlight and, if used,radiant heating devices. The storage temperature shall becontrolled by use of heating and cooling devices, as necessary.Record the temperature using a maximum-minimum thermom-eter. If cardboard molds are used, protect the outside surface of
42、the molds from contact with wet burlap or other sources ofwater.NOTE 8Asatisfactory moisture environment can be created during theinitial curing of the specimens by one or more of the followingprocedures: (1) immediately immerse molded specimens with plastic lidsin water saturated with calcium hydro
43、xide, (2) store in properly con-structed wooden boxes or structures, (3) place in damp sand pits, (4) coverwith removable plastic lids, (5) place inside plastic bags, or (6) cover withplastic sheets or nonabsorbent plates if provisions are made to avoiddrying and damp burlap is used inside the enclo
44、sure, but the burlap isprevented from contacting the concrete surfaces. A satisfactory tempera-ture environment can be controlled during the initial curing of thespecimens by one or more of the following procedures: (1) use ofventilation, (2) use of ice, (3) use of thermostatically controlled heatin
45、g orcooling devices, or (4) use of heating methods such as stoves or lightbulbs. Other suitable methods may be used provided the requirementslimiting specimen storage temperature and moisture loss are met. Forconcrete mixtures with a specified strength of 40 MPa 6000 psi orgreater, heat generated du
46、ring the early ages may raise the temperatureabove the required storage temperature. Immersion in water saturated withcalcium hydroxide may be the easiest method to maintain the requiredstorage temperature. When specimens are to be immersed in watersaturated with calcium hydroxide, specimens in card
47、board molds or othermolds that expand when immersed in water should not be used. Early-agestrength test results may be lower when stored at 16C 60F and higherwhen stored at 27C 80F. On the other hand, at later ages, test resultsmay be lower for higher initial storage temperatures.10.1.3 Final Curing
48、:10.1.3.1 CylindersUpon completion of initial curing andwithin 30 min after removing the molds, cure specimens withfree water maintained on their surfaces at all times at atemperature of 23.0 6 2.0C 73.5 6 3.5F using water stor-age tanks or moist rooms complying with the requirements ofSpecification
49、 C511, except when capping with sulfur mortarcapping compound and immediately prior to testing. Whencapping with sulfur mortar capping compound, the ends of thecylinder shall be dry enough to preclude the formation of steamor foam pockets under or in cap larger than 6 mm 14 in. asdescribed in Practice C617/C617M. For a period not to exceed3 h immediately prior to test, standard curing temperature isnot required provided free moisture is maintained on thecylinders and ambi
